Less than you might think. USN doctrine was to rely mainly on torpedoes, not guns (unlike the Germans).[/QUOTE]
Might be problematic with the given status of quality of US torpedoes in the first half of the Pacific War. More than half of the torpedoes simply failed to do what they were designed for and that is excluding the ones failing completely to run at all. (Some even sank their own launchingplatform) Only as far as mid 1944, the torpedoproblem was solved, meaning in the times between Pearl harbor and half 1944, the USN subs had to use poor quality torpeodes and mostly had to use guns against single sailing targets, such as small cargoships, frequently used by the Japanese to run between islands.
Might be problematic with the given status of quality of US torpedoes in the first half of the Pacific War. More than half of the torpedoes simply failed to do what they were designed for and that is excluding the ones failing completely to run at all. (Some even sank their own launchingplatform) Only as far as mid 1944, the torpedoproblem was solved, meaning in the times between Pearl harbor and half 1944, the USN subs had to use poor quality torpeodes and mostly had to use guns against single sailing targets, such as small cargoships, frequently used by the Japanese to run between islands.